May 17, 2006
Mercury Decision: 'Expert Witness' Misled The Court
Last week's landmark canned-tuna court decision was full of twists and turns. Who would have thought that mercury in fish is "naturally occurring"? Or that tuna, long the environmental movement's whipping-fish (see here, here, and here), actually had very low mercury levels to begin with? Well, actually, we knew that, and now the California Attorney General knows it too. But perhaps the oddest development came in the form of an "expert witness" whose testimony the judge dismissed as "misleading" as well as "unreliable" and "biased" -- and who made claims (offered, the judge wrote, "under penalty of perjury") which turned out to be phony.
Meet Dr. Deborah Rice, a former Environmental Protection Agency toxicologist who now works for the Maine Bureau of Health. While at the EPA, Dr. Rice was one of the three scientists responsible for determining the agency's hyper-precautionary mercury "Reference Dose." In the California case, she tried to argue that the state's Maximum Allowable Dose Limit (MADL) for mercury in fish should be set so low that (again, in the judge's words) "all servings of fish and shellfish larger than literally a grain of rice would require a warning."
In order to make her case for this ridiculous standard, the court wrote, Dr. Rice
claimed that the World Health Organization had "observed" paresthesia [prickling sensations] in persons poisoned ... at a daily dose of 50 and 200 micrograms. She was specifically asked, and testified under penalty of perjury that the paresthesias were "observed not modeled."
So according to Dr. Rice, the WHO has evidence that a vanishingly small dose of mercury has caused neurological damage in real, live people. But wait -- the judge continues:
Dr. Rice misstated the WHO's analysis ... Only when confronted with the WHO report did Dr. Rice acknowledge that the 50 and 200 micrograms per day levels were [computer] modeled, not observed, and were for cumulative exposures over a long period of time, and not single exposures.
The judge also criticized Dr. Rice for basing her calculations on a study in Denmark's Faroe Islands:
The Faroe Islands study did not identify and quantify confounding factors and did not have complete follow-up of all children in the study. The Court is particularly troubled by the fact that when the researchers controlled for PCB exposure, there was no statistically significant correlation between methylmercury and performance on the Boston Naming Test, which served as the basis for Dr. Rice's MADL.
The judge pointed out that Dr. Rice -- the best-qualified expert the State of California could find to hype the health impact of mercury in fish -- "had no experience performing a quantitative risk assessment under Proposition 65 and had never calculated an MADL" and is "not Board Certified."
